Rail for a window covering



FIG. 1 is a perspective view of a portion of a rail for a window covering;

FIG. 2 is a left end view thereof, which is the same as the right end view thereof;

FIG. 3 is a front view thereof, which is the same as the rear view thereof;

FIG. 4 is a top view thereof; and,

FIG. 5 is a bottom view thereof.

The broken lines form no part of the claimed design but indicate that the actual rail may extend for a greater length than the portion of the rail that is being claimed. 

CLAIM The ornamental design for a rail for a window covering, as shown and described. 